Never mind the b/c. He lost his US citizenship when he was adopted in Indonesia.
One needs to provide a birth certificate to get a U.S. passport. How did Obama get a passport?
If he was born overseas, and/or lost his citizenship when adopted in Indonesia, then didn’t he have to become a naturalized citizen to regain his citizenship at some point? And wouldn’t he have had to provide that paperwork to get his passport?
I think his passport file would contain some answers to these questions.